RU2769878C1 - Milk ball viscometer - Google Patents

Abstract

FIELD: physics; food industry.

SUBSTANCE: ball viscometer for milk contains measuring cylinder (3) in cavity of thermostat (2) with thermometer (5), magnetic ball-indenter (4), two Hall sensors (6, 7) installed in thermostat (2) housing, permanent magnet (10), servo drives (11, 12), post (8), lever (9), control unit (13). Magnet (10) moves along post (8) by means of servo drive (11). Post (8) is deflected under the action of servo drive (12). Ratio of ball diameter:cylinder diameter is in range of 1:1.2–1:1.5.

EFFECT: enabling analysis of milk-clotting properties of enzymes, bacterial starters and doses thereof.

3 cl, 4 dwg

Description

The invention relates to the field of rheology, namely to portable ball viscometers for determining the viscosity properties of fluids, in particular milk, and can be used, for example, to analyze the activity of milk-clotting enzymes and bacterial starter cultures, to study the dynamics of coagulation of various milk samples, which predetermines its cheese suitability, and also to identify the optimal temperature parameters of the coagulation process, etc.

Known capillary viscometers, characterized by a high limit (up to 10%) of the permissible error in the measurement of viscosity (See GOST R 54077).

Known ball Geppler viscometer includes a cylinder of heat-resistant glass filled with liquid, the viscosity of which must be measured and the ball moving in the cylinder when it is tilted at an angle of 10°. The duration of the movement of the ball between two marks applied on the cylinder is a function of the viscosity of the investigated liquid. The time of passing the ball is fixed by a stopwatch. [Malkin A.Ya., Isaev A.I. Rheology: concepts, methods, applications / Per. from English. - St. Petersburg: Profession, 2007. - 560 pages, ill.].

The accuracy of viscosity measurement when using this type of viscometer is higher than that of capillary viscometers. So, when working with Newtonian fluids (liquid with constant viscosity), the limit of permissible relative error is 2%.

The disadvantage of these viscometers is that the accuracy of the measurement is affected by the reaction time of the operator at the speed of turning the cylinder during measurements, especially when working with non-Newtonian liquids characterized by variable viscosity over time, such as coagulating milk.

Known ball viscometer company HAAKE, where as a cylinder for a falling ball using a medical syringe, in which the sample volume is 0.3-0.5 cm ³ . A magnet that rotates at a constant speed and passes behind the syringe lifts the ball twice per minute. When the magnet turns away from the ball and does not act on it, the ball falls into the liquid. The ball fall time is measured automatically by means of position sensors (optical sensors) with the results presented digitally on the monitor. Every 30 seconds the magnet returns, it lifts the ball and the cycle repeats. [Schramm G. Fundamentals of practical rheology and rheometry / Per. from English. I.A. Lavygin; ed. V.G. Kulichikhina. - M.: KolosS, 2003. - 312 p.].

In a viscometer of this design, the falling time of the ball is measured automatically, which improves the measurement accuracy.

However, this viscometer is not suitable for working with opaque liquids, since the ball fall time is recorded by optical position sensors, which predetermines the impossibility of using it when working with milk, in particular, for example, to study the dynamics of the milk coagulation process under the influence of various factors such as type and dose enzyme or bacterial starters or coagulation process temperature, etc.

Known ball viscometer containing a working fluid (steel ball) placed in a vertical measuring cylinder made of non-magnetic material, on the surface of which position sensors (inductive sensors) are installed, a magnetic field source (electromagnet) for lifting the ball to the upper position, a software device for periodic reduction into the action of the source of the magnetic field and the removal of data (time of the fall of the ball) (see A.C. USSR No. 252722, IPC G01N 11/10, declared 11/28/1967, published 09/22/1969.

The inductive position sensors used predetermine the possibility of using this viscometer to work with opaque liquids, in particular, milk.

The disadvantage of this viscometer is the following. In an inductive sensor, a magnet passing by the coil induces a current in it, as a result of which the signal increases linearly (as the electromagnet approaches) and the signal is recorded only when a certain threshold value is reached, while the biochemical processes of milk coagulation proceed at a high speed. Therefore, the use of this viscometer when working, for example, with coagulating milk is characterized by low viscosity measurement accuracy and does not allow tracking the coagulation process in time due to the fact that the signal registration will not keep up with the speed of the process.

In addition, the measuring system given in the description makes it possible to measure the duration of the fall of the ball with low accuracy, since it is based on the use of a microammeter as an indicator of the measurement results, the accuracy of which allows fixing the result with an accuracy of no more than two digits (microammeter dial), which is not enough for precision measurements, where the viscosity of liquids varies hundreds of times.

The task to be solved by the claimed invention is to expand the functionality of the viscometer with a reduced error in measuring the viscosity, which ultimately will optimize the technological process of cheese production.

The optimization of technological processes is based on the fact that the claimed viscometer for milk allows (due to the possibility of tracking the course of the coagulation process over time with high accuracy of viscosity measurement) a comparative analysis of the milk-clotting properties of enzymes, bacterial starters and their doses, selecting the most suitable one for cheese production. them for a particular type of milk used, and also allows you to choose the optimal temperature regime for the course of the coagulation process and determine the cheese suitability of milk obtained from different types of animals.

The specified technical result is achieved by the fact that the ball viscometer of milk includes a measuring cylinder for the test liquid placed in the cavity of the thermostat and equipped with a thermometer, a magnetic ball-indenter, two Hall sensors installed in the thermostat housing, a manipulator for dropping and lifting the ball-indenter made in the form of a deviating under by the action of the rack servo drive with a fixed on it, with the possibility of sliding, a lever with a permanent magnet interconnected with a servo drive for vertical movement of the magnet along the rack, while both servo drives, Hall sensors and a temperature sensor are connected by wire to a software control and display unit, and the ratio of the ball diameter : cylinder diameter are within 1:1.2-1:1.5. The thermostat is made of a non-magnetic material, for example, aluminum, while the thermostat, the servomotor for deflecting the rack and the software control and display unit are mounted on a common base.

The use of Hall sensors in the claimed viscometer as sensors of the position of a magnetic ball-indenter allows, due to the fact that in the Hall sensor the signal appears instantly (jumpwise), to significantly increase the accuracy of measuring the position of the ball in the viscometer, in contrast to inductive sensors, where the signal increases linearly and its registration occurs only upon reaching a certain threshold value, not having time to track the high-speed biochemical process of milk coagulation in time.

In addition, studies have shown that the ratio of the diameters of the ball and cylinder affects the rate of fall of the ball as a function of viscosity. The optimal limit of the ratios, as studies have shown, is the diameter of the ball: the diameter of the cylinder is 1:1.2-1:1.5. The ratio of 1:1.1 caused increased turbulence during the fall of the ball, distorting the picture of the speed of its fall with an increased error in measuring viscosity by an average of 1-2%, and at a ratio of 1:1.6, the consumption of expensive components of milk, enzymes, and starter increased, which is unacceptable in economic terms. considerations and without increasing the measurement accuracy.

On FIG. 1 shows the claimed viscometer.

On FIG. 2 is a graph illustrating the comparative process of milk coagulation under the action of three milk-clotting enzymes.

On FIG. 3 is a graph illustrating the influence of temperature on the milk coagulation process.

On FIG. 4 is a graph illustrating the clotting process of three milk samples.

A ball viscometer for milk includes a base 1 on which a thermostat 2 is fixed with a cavity in which a measuring cylinder 3 (for example, a glass test tube) is installed with the test liquid and an indenter ball 4, which is a permanent magnet. The liquid temperature is monitored by temperature sensor 5. Thermostat 2 is made of aluminum and is equipped with upper 6 and lower 7 magnetically sensitive Hall sensors. In the immediate vicinity of the thermostat 2, a manipulator is installed, consisting of a rotary (deflecting) rack 8 on which a permanent magnet 10 is fixed on the lever 9 with the possibility of sliding along it, a servo drive 11 for moving the magnet 10 to the lower and upper positions, a servo drive 12 for deflection and return to the initial position of the rack 8, while both servos, Hall and temperature sensors are connected by wire to the control and indication unit 13 fixed on the base 1. The data of the process under study are displayed on the monitor 14 of the control unit in the form of graphs or numbers.

The viscometer works as follows.

Example 1. The general principle of operation of a viscometer using an example illustrating the comparative process of milk coagulation under the action of three milk-clotting enzymes.

Before starting work, using a programming device (control and indication unit), the operator sets the desired frequency of measurements (for example, every 2 seconds) and the temperature of milk coagulation (for example, 35 ° C). The test milk is poured into the measuring cylinder, the indenter ball 4 (magnetic ball) is placed in it and thermostated for 5-7 minutes until the desired temperature is reached. A predetermined amount of enzyme solution (for example, 50 microliters) is introduced into the test tube with a microsyringe. In the mode of readiness for measurements, the manipulator, on command from the control and display unit 13, sets the ball-indenter 4 by means of the servo drive 11 in the upper part of the measuring cylinder 3 (Fig. 1) - the initial position. Further, the manipulator, by means of a servo drive 12, controlled by the control and indication unit 13, sharply takes the rotary stand 8 to the side (position during measurement), interrupting the magnetic contact between the magnet 10 and the ball-indenter 4, while the ball goes down under the action of gravity. When the ball-indenter passes the upper sensor 6, a start pulse is generated and a timer is started in the microprocessor of the control and indication unit. The timer starts counting time in milliseconds. When the ball-indenter passes the lower sensor 7, the timer stops. Thus, the time interval of the fall of the indenter ball at a known distance of the location of sensors 6 and 7 is measured.

The results of counting the fall time of the indenter ball are converted by the microprocessor 14 into viscosity units and displayed on the monitor screen of the control and display unit 13 in the form of numbers and a graph (Fig. 2). Upon completion of the measurement process, at the command of the control unit, the manipulator lowers the lever 9 with a power magnet 10 down by means of a servo drive 11, while the ball and the power magnet come into magnetic contact and through the servo drive 11 the ball-indenter 4 returns to its original position and the measurement cycle is repeated when using the next enzyme under study, the quality of which needs to be assessed. The result is a graph of the form shown in Fig. 2, where line 1 corresponds to an enzyme with low activity and, accordingly, low quality, line 2 - to an enzyme with medium activity, and line 3 - to a high-quality enzyme. According to the resulting graph, one can judge the activity of samples of milk-clotting enzymes and compare their quality with each other.

Example 2 A ball viscometer can be used to study the rate of milk clotting under the action of milk clotting agents depending on the temperature at which the clotting process takes place (Fig. 3). Using a software control and display unit, the operator sets the frequency of measurements and the desired milk temperature. A milk-clotting agent, for example, rennet, is added to the obtained sample of milk, heated to the desired temperature, in an amount typical for cheese making. A portion of such milk is transferred into the measuring cylinder 3 with the ball-indenter 4 immersed in it, the cylinder is placed in the thermostat 2, which maintains the desired temperature, and immediately begin to measure the viscosity as described in example 1. Data on the change in the viscosity of milk over time are displayed on the monitor of the block control 14. Then, in a sample of the same milk, heated to the next temperature value being studied, the same rennet is added in the same amount and the measurement cycle is repeated. The result is a graph of the form shown in Fig. 3, where line 1 corresponds to a low rate of milk clotting, which indicates an unsuccessful choice of temperature by the operator (too low or too high) for rennet to work, line 2 - a relatively higher rate of milk clotting at the next temperature value and line 3 - the highest speed coagulation of milk at a given temperature. According to the obtained graph, it is possible to choose the optimal temperature for working in milk for a specific milk-clotting agent.

Example 3 A ball viscometer can be used to analyze the quality of milk, for example, its cheese suitability (Fig. 4). Using the program control unit 13, the operator sets the frequency of measurements and the temperature of the milk. A milk-clotting agent, for example, bacterial starter, is added to the studied sample of milk heated to a certain temperature, in an amount typical for cheese making. A portion of such milk is transferred to the measuring cylinder 3 with the indenter ball 4 immersed in it, the cylinder is placed in the thermostat 2 and the viscosity measurement is started as described in example 1. Data on the change in milk viscosity over time are displayed on the monitor 14 of the control unit 13. Then the next the studied sample of milk, the quality of which must be assessed, at the same temperature, the same bacterial starter is introduced in the same amount and the measurement cycle is repeated. The result is a graph of the form shown in Fig. 4, which shows the time curves for the fall of the indenter ball during milk clotting. The activity of milk clotting is estimated by the length of time the ball-indenter falls (milk viscosity) upon reaching a predetermined level (for example, Fig. 4 - 1.5 s). this time is for different milk samples (Ta, Tv and Ts) on the graphs.

Under given conditions (enzyme dose, coagulation temperature), the activity of the milk in relation to the enzyme used is estimated from the duration of the fall of the ball in the milk to be coagulated.

In the given example, the most active was the sample of milk No. 3, its time until reaching the duration of the fall of the ball 1.5 seconds (reference value) was less than 30 seconds. Milk No. 2 was slightly less active. The ball drop time of 1.5 s was reached 40 s after the addition of the enzyme. Milk sample No. 1 had the least activity. The duration of the fall of the ball of 1.5 s was achieved at 65 seconds from the moment the enzyme was added.

Line 1 corresponds to rennet sluggish milk, the quality of which is low for cheese making, line 2 to medium quality milk suitable for making soft cheeses without ripening, and line 1 to high quality milk suitable for making elite hard cheeses. According to the resulting schedule, one can judge the suitability of a batch of milk for making cheese, as well as adjust the dose of the enzyme according to special tables or a formula. A similar analysis of the graphic material is carried out according to the graphs of examples 2 and 3.

Thus, the design features of the claimed viscometer make it possible to expand its functionality with a reduced viscosity measurement error, which ultimately can ensure the optimization of technological processes for cheese production.

Claims (3)

1. Ball viscometer for milk, characterized in that it includes a measuring cylinder for the test liquid, placed in the thermostat cavity and equipped with a thermometer, a magnetic indenter ball, two Hall sensors installed in the thermostat housing, a manipulator for dropping and raising the indenter ball, made in the form of a rack deviating under the action of a servo drive with a lever with a permanent magnet fixed on it, with the possibility of sliding, interconnected with a servo drive for vertical movement of the magnet along the rack, while both servo drives, Hall sensors and a temperature sensor are connected by wire to a software control unit and indication, and the ratio of ball diameter : cylinder diameter is in the range of 1:1.2-1:1.5. 2. Viscometer according to claim 1, characterized in that the thermostat is made of a non-magnetic material, such as aluminum. 3. The viscometer according to claim 1, characterized in that the thermostat, the servo to deflect the rack and the control and display unit are mounted on a common base.

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